Electro-mechanical machines are widespread. Rotating electro-mechanical machines, such as dynamoelectric machines (generators and alternators) and motors, are particularly prevalent, in both private and industrial applications. Rotating electromechanical machines usually include a stationary member, known as a “stator,” about which a rotating member, known as a “rotor,” turns. In certain types of machines, the rotor (sometimes referred to as an “armature”) rotates within the stator (or “field”), which produces a rotating magnetic field. In other types of machines, the rotor produces a magnetic field, which produces an electrical current in the stator. Both stators and rotors may include one or more windings of conductors (for example, field windings) that carry current and/or generate magnetic fields and forces.
Several different rotating electro-mechanical machine designs exist. One common design is the Lundell, or “claw-pole,” design. The claw-pole design is often used for dynamoelectric machines, such as alternators. In a claw-pole machine, the rotor includes claw-shaped pole segments (usually a pair of segments) located around one or more field windings. The pole segments have claw-shaped magnetic poles and are affixed around the winding such that the claws mesh together. FIG. 1 shows a conventional claw-pole rotor assembly 100 that may be used in an alternator. As illustrated, a pair of claw-pole segments (110) surround a field winding (120) and the claws (112) of the segments (110) intermesh.
Given the thermal conditions in which claw-pole machines often operate, proper cooling is vital to ensure proper and prolonged operation. Internal cooling fans are commonly used to cool claw-pole machines. For example, referring again to FIG. 1, rotor assembly 100 includes two internal cooling fans (131, 132). Internal cooling fans, such as fans 131 and 132, are usually attached to the pole segments by welding or frictional clamping.
Conventional internal cooling fan attachment techniques are deficient in a variety of aspects. With conventional techniques, the choice of internal cooling fan material is restricted. For example, in order to weld a fan to a pole segment, the fan must be formed from a suitable material, such as steel. Further, conventional attachment systems may be prone to fatigue and/or failure. Clamps and welds may degrade and eventually fail during prolonged operation. In addition, present attachment techniques do not account for fan alignment.